Vegetation shapes alpine ground-dwelling macro-invertebrate communities: A case study from the Stilfserjoch/Stelvio National Park (Martell/Martello, South Tyrol, Italy)

There are few studies on ground-dwelling invertebrates from alpine ecosystems, often with only one or a few samplings per growing season. However, to get a most comprehensive picture of the faunal community present, samplings throughout an entire season are needed. Here we present data on ground-dwelling macro-invertebrate communities from four characteristic alpine habitats (i.e., pasture, dwarf shrub heath, grassland, and fragmented grassland) along a short elevation gradient. They were monitored continuously over almost an entire growing season (June to October) using pitfall traps. We found considerable differences between the four habitat types, with the pasture having the lowest abundances (i.e., activity densities as individuals per sampling day). At the other three sites, biodiversity indices (i.e., Shannon and Evenness) increased with elevation, while the activity densities of the main taxa Araneae, Myriapoda and Coleoptera decreased; they showed a peak activity in mid-July to mid-August. The faunal communities, despite sharing many families among habitat types, showed a clear separation of three groups in the ordination plot (CCA), with the pasture and grassland harbouring similar communities and being well separated from the ones of the dwarf shrub heath and the fragmented grassland. In this study we found distinct ground-dwelling macro-invertebrate communities in four characteristic alpine habitats, despite their spatial proximity. We found the vegetation (i.e., here plant life-forms as proxy) being a strong driver shaping faunal communities. Additionally, the quite intensive grazing activities on the pasture might have negative impact on the invertebrates, while low/no grazing at the more natural higher plots (i.e., grassland and fragments) and a high habitat heterogeneity (at the fragmented grasslands) might be reflected in high numbers of abundances and biodiversity indices. Our study underlines the importance of assessing alpine soil fauna by performing many samplings throughout a growing season to depict most complete faunal communities